Motion sensing controlled lighting and decorative outdoor light fixtures are very popular. Often customers would like to have a product which is decorative, but which also incorporates automatic motion sensing control. A number of problems arise when integrating a motion sensing feature into the light fixture.
From a sensing perspective, the ideal solution is a sensor head which can be readily positioned and aimed so that the sensed coverage area is precisely where it is desired. Unfortunately a movable sensor head is not aesthetically pleasing on a decorative fixture; consequently the desired approach requires a motion sensor that can be concealed within a portion of the light fixture.
In order to achieve a concealed approach, a fixed sensor is often used which can unfortunately result in many compromises in sensor performance. The biggest compromise is that the sensor has no mechanical adjustment and therefore the coverage pattern is fixed. This is ultimately a compromise in terms of the coverage area. Using traditional lens design approaches, the coverage pattern is an approximate fan shape. However, most areas where the coverage is needed such as a yard are not shaped like a fan. As such, it would be more desirable to have a rectangular coverage pattern.
Furthermore, a large problem with a fixed coverage pattern are the false activations that can occur. In a typical application, the house on which the fixture is mounted can be some 40 feet from a street. Although the stated coverage range may typically be 30 feet, under some environmental conditions, such as a passing car that is at a substantially different temperature than the ambient temperature, the sensor may be able to detect the car at ranges far beyond the 30 foot stated range of the sensor. This result can cause undesirable false activation when cars pass by. In short front yards, the street may be readily within the range of the sensing area virtually all of the time, causing continual false activation.
False activations can be reduced by reducing sensitivity in motions sensors that have sensitivity adjustment capability. However, sensitivity adjustments can unfortunately further reduce the sensitivity to motion of people, which may be undesirable.
Thus, the need exists for solutions to the above problems with the prior art. The systems, devices, and methods of the present invention solve some complicated mechanical problems within a small space to deliver a mechanism that allows the internal sensor to be tipped to adjust the pattern of coverage, especially the maximum distance at which it can sense motion, because the sensing beams can be angled to strike the ground thus preventing the coverage pattern from extending beyond the target area.